Certain heteroaromatic diphenyl ethers are disclosed as herbicidal agents in European Patent Publication No. 178,708. The publication discloses certain substituted phenoxy benzoheteroaromatic compounds such as benzotriazoles, benzoxadiazoles, benzothiadiazoles, benzoxazoles and benzothiazoles as herbicides. It has now been found that when aryloxy benzotriazoles are substituted at the N.sup.1 position by certain substituted alkyl moieties, an unexpectedly increased level of herbicidal activity is obtained.